One of the major unanswered questions in the calcified tissues field is how and why mineral is deposited at discrete sites, and conversely what normally prevents the unwanted deposition of mineral at other sites. The goal of this investigation continues to be the elucidation of the mechanism of biologic calcification. Specific emphasis will be placed on (1) the factors controlling initial mineral deposition and (2) the factors regulating proliferation and growth of the mineral. The proposed studies will examine cellular factors (membrane lipid composition), hormonal factors (vitamin D), extracellular matrix factors (the non-collagenous proteins: - phosphoproteins, sialoproteins, proteoglycans, proteolipids, and blood-derived proteins), and chemical factors (Ca x P) concentration) which may play a role in controlling initial mineral deposition and/or growth and proliferation of hydroxyapatite crystals. Studies will be based on previously developed lipid-induced calcification, gel growth, seeded growth and in vitro cell mediated calcification systems, as well as analysis of matrix vesicle and animal models. Analytical techniques to be used include: x-ray diffraction and infrared analyses, chemical analyses, and light, scanning and transmission electron microscopy. The ultimate goal of this project is to elucidate the details of the cascade of events involved in physiologic calcification. These details are crucially needed for the development of new and improved therapies for diseases of bones and teeth characterized by impaired, defective, or excessive mineral deposition.